Process for cracking petroleum oil



[July 1.3, 1926*.-

` 1,592,560 v C. P. DUBBS` l PROCESS FOR CRACKING PETROLEUI DIL Filed Nov. 27, l1922 Waneer sara/Ne ,namen new/swarm Patented July 13,1926.

UNITED lSTATES PATENT OFFICE.

CARBON P. DUBBS, OF WILMETTE, ILLINOIS, ASSIGNOR TO THE UNIVERSAL OIL PROD- UCTS COMPANY, F CHICAGO, ILLINOIS, A CORPORATION OF SOUTH DAKOTA.

PROCESS FORORACKING' PETROLEUM OIL.

Application led November 27, 1922. Serial No. 608,401.

This invention relates to improvements in a process for cracking petroleum oils and refers more particularl to a process of converting relatively hig boiling point oils into oils of a llower boiling point such as gasolene and the like. Among the salient objects of the 'invention are to provide a process in which oils are separately charged to two distinct portions of the heating zone of a cracking apparatus and a process in which the heat given up in the dephlegmation of the oil vapors evolved in the cracking operation is used to volatilize an ex traneous oil which is passed through the portion of the a paratus in which the vapors undergo de h egmation and condensation.

The sing e figure is a diagrammatic side elevational view of the apparatus -with parts broken away and parts in section.

Referring to the apparatus and the manner in which oil is coursed therethrough, there is supplied an oil charge from any convenient source through the line 1 which is pumped by means of a char ing pump 2 through the line 3 controlled y a valve 4 to the prelieating tubes 5. These preheating tubes are positioned in the upper or cooler portion of the furnace and utilize the heat of the waste combustion gases, relieving them of heat which would normally be lost.

l The oil after passing downwardly throu h this continuous coil which runs longitu inally of the furnace 6, 'is directed from the discharge end of the c oil through the line 7 which is connected to a line 8 which Vreturns the reflux condensate from the lower leg of the dephlegmator 9. In this line 7 'is positioned a valve 10 by means of whichthe oil may -be permitted to pass to the line 8 or be directed into the pipe 11 which terminates in the form of a spray 12 in the upper pbrtion of the dephleginator 9, thus the preheated loil ma be supplied directly to the second section o the heating tubes through the' line 8 or utilized as a reiuxing medium in the de hlegmating column. If the oil is directed t rough the line 7 `to the line 8 by closing the valve 13 and opening the valve the preheated oil will-be coursed through the second-section 14 of the heating coils positionedin the lower or hotter portion of 'the furnace 6- and there be` raised to a conversion temperature. This heated oil in a conversion state'f-passes thence through the transferfline 15 tothe expansion or conversion chamber 16 which is fitted with trycocks 17 by means of whichmay be ascer` tained the liquid level in the chamber at all times. The chamber is heavily insulated to prevent loss of heat through radiation and is provided with Athe liquid residuum drawofi' lines 18 controlled by valves 19. These lines may be successively used as the carbon collects in the bottom of the chamber for drawing oif .the unvaporized relatively heavy residual substances from the chamber. The vapors evolved from vthe body of oil in the expansion chamber pass off through the vapor line 20 regulated by a valve 21 and rise through the dephlegmating column n 9 where they are subjected to the reiiuxing action of the relatively cool gil passing through the coil 22 and also by coming in intimate contact with cooler oil introduced by the spray pipes 12 and 23, the spray pipe 12 may be employed for introducing the reheated oil from the upper tubes of tlie urnace and the spray 23 for returning portions of the liquid distillate from the final collecting tankv as will hereinafter be explained. The uncondensed vapors passing olf from the top of the dephlegmating column are directed through the line 24 controlled by valve 25 to the upper drum 26 of a heat interchanger. In this heat interclianger the vapors are passed tirst from the upper drum through connecting tubes 27 to the lower drum 28 while there is circulated about the connecting tubes 27 relativel cool oil introduced through a line 29. rom the lower header 28 the condensed and uncondensed oil constituents pass down through the ipe 30 controlled by a valve 31 and circu ate through the condensing coil `32 positioned in the water condenser box 33.

After passin through'` this final stage lected in the receiving tank 34 which communicates withl the discharge end of the condenser coil by means of a i 35 regulated by avalve '36. The receiving tank.34 is equipped with a liquidv draw-off valve 37, a pressure relief valve 38, pressure gauge 39 and a liquid level gau e40: .A second liquid drawof line 41 in w ich is mterpoeed a valve 43 communicates with the suction side of the ump 43 by means of which the liquid distillate collecting in the receiving tank may/be returned through the line 44 controlled by avalve 45 and introduced by of. condensation t e liquid distillate is col# means of the spray 23 into the top of the dephlegmating column.

rl`he oil introduced through the line 29 may be a separate or extraneous oil from that undergoing treatment in the process above described. This extraneous oil is preheated by circulation about the tubes 27. This oil is then drawn off from the upper part of the preheater through the line-46 regulated by a valve 47 and is circulated through the closed coil 22 positioned in the dephlegmating column 9. In this portion of the apparatus this extraneous oil serves as a dephlegmating medium and absorbs the heat given up by the vapors passed to the dephlegmating column from the chamber 16. This heat is normally sufiicient to raise the extraneous oil to a volatilizing temperature, the character of such oil and the amount introduced through the line 29 being regulated to efi'ect these results to the extent desired. This heated fluid oil is passed through the transfer line 48 connected to the discharge end of the coil 22 and is introduced into the fractionating column 49 through either of the secondary connections 48, 48b or 48. The assage of the oil constituents through the ractionating column 49 is interrupted by a series of perforated pans 51, causing an increased dispension o the Oil and there may be also introduced to the column and brought in intimate contact with these vapors a liquid distillate introduced by the spray pipe 52. Thus the vaporous constituents evolved from such extraneous oil are subjected to a refluxing action and subsequent thereto pass oft through the vapor line 53 in which is interposed a valve 54 to the condensing coil 55. After being condensed therein they are collected as liquid distillate in the receiving tank 56. This tank similarly to the tank 34 is equipped with a liquid drawoff valve 57, a pressure relief valve 58, pressure gauge 59, and liquid level gauge 60. The distillate may be returned from this tank by means of a pipe 61 controlled by a valve 62 and recharged into 'the top of the fractionating column 49 through the pump 63 and return line 64. Trycocks 6,5 are positioned in the lower portion of the fractionating column 49 for determining the liquid level therein. A lower drawof valve 66 connected `to any convenient storage is utilized to control this liquid level. If desired, this liquid collected .in the fractionating column may be returned and charged with the oil to the heating tubes 5 or 14.

As ex lained the partially expended gases in the rnace are used to preheat the incoming charging oil which is then united with the reflux condensate and subjected to a conversion temperature while flowing through the hottest portion of the furnace or a further preheating ofthe charging oil may be effected by diverting this preheated oil into the top of the dephlegmating column and there bringing it into intimate contact with the heated oil vapors. In this latter operation the oil subsequent to being introduced to the dephlefrmating column will flow back with what refIux condensate it may collect and be charged to the section 14 of the heating coil in the furnace. Further utilization of the heat given up by the vapor in the dephlegmating column 9 is effected by supplying this heat to the extraneous oil charged first to the heat interchanger through line 29 and then circulated through a. closed coil 22 in the dephlegmating column 9. In the heat interchanger the temperature of the oil is substantiall raised so that its circulation through the ephlegmating column will serve to raise the temperature of the oil to its evaporating temperature. This evaporation may or may not be accompanied by more or less conversion or cracking. g

The secondary' system may be utilized in topping crude petroleum, redistillation, or for the treat-ment of different types of oils with provision subsequent to treatment for collecting separately the distillates of unlike character produced in the separate systems.

The process is therefore economical to operate and oils of different character may be treated in the same apparatus without mixing. Further. the control which may be had by manipulation of the valves in the connecting lines between the different stages serves to materially improve the character of the reaction and the quality of the distillate obtained.

I claim as my invention 1. A process for treating hydrocarbon Sll oil, consisting in initially passing the cliarging oil in a restricted stream through that portion of a heating zone maintained at the lowest temperature, in then uniting with the charging oil reflux condensate formed in the process and in passing the commingled charging oil and reflux condensate in a restricted stream through that portion of the heating zone maintained at the highest temperature, in delivering the highly heated oil from said stream into an enlarged reaction zone from which no unvaporized oil is permitted to return to either ofsaid streams, in passing vapors from said enlarged zone to a dephlegmator wherein portions thereof are condensed forming said reflux condensate,

in passing uncondensed vapors from the dephlegmator to a final condenser, in collectingthe resulting distillate and in maintaining a super-atmospheric pressure on the oil undergoing conversion. l

2. A- continuous -process for cracking hydrocarbon oil, consisting in initially passing the charging oil in a restricted stream through a. portion of a VVheating zone, in then uniting said restricted stream of charging oil with a stream of reflux condensate formed in the process and in passing the commingled charging-coil and reflux condensate in a second restricted Stream constituting a continuation of the first stream wherein said commingled charging oil and reflux condensate is raised to a cracking temperature, in delivering the highly heated ,commingled reflux -condensate and charging oil to an enlarged reaction zone from which no unvaporized oil is permitted 'to return to either of said streams, in frac tionating the vapors evolved from the oil to separate therefrom the insufficientlyA cracked 'fractions Whichform. said reflux condensate and in maintaining a super-atmospheric pressure on the oil undergoing conversion. 3. .A continuous process for converting heavier hydrocarbons into lighter hydrocarbons, consisting in initially advancing a charging oil in a restricted stream through a portion of a heating zone, in then introducing 'to the restricted stream of charging oil a streamof reflux condensate formed in the process and in then assing the commingled charging oil and re ux condensate in a restricted stream through a second portion of the heating zone wherein the commingled charging oil and reflux condensate are raised to a cracking temperature, in then introducing the highly heated conimingled reflux condensate and charging oil into an enlarged reaction zone wherein conversion and substantial vaporization occurs, in passing 'the evolved vapors to a dephlegmator Wherein `the insufficiently cracked fractions are condensed forming said reflux condensate, in taking olf the uncondensed vapors from said dephlegmator for condensation and collection and in maintaining a self-generated 'vapor pressure on the oil undergoing conversion. c

4. A process for cracking hydrocarbonoil, consisting .in passingthe oil in a restricted stream rthrough a heating zone wherein it is raised to a cracking temperature, in delivering the highly heated oil from said stream to an enlarged reaction zone from which no unvaporized oil is permitted to return to said stream, in passing vapors evolved from the oil to a dephlegmator wherein the insufficiently cracked fractions are condensed forming reflux condensate, in introducing such reflux condensate to said stream of oil at a point intermediate its travel through said heatingzone to again subject said reflux condensate to av cracking temperature, in taking olf the uncondensed vapor l from said dephlegmator for condensation and' co1- lection and in maintaining a self-generated 'super-atmospheric vapor pressure on the oil undergoing conversion.

5. A process for cracking hydrocarbon oil, consisting in maintaining a body of oil under cracking conditions of temperature and pressure in an enlarged convlersion zone Where vaporization occurs, in removing the vapors from such zone and., subjecting the same to reflux condensation to separate the sufficiently cracked from vthe insuliciently cracked vapors, in introducing charging oil to a heating coil at a point thereof to cause such charging oil to initially flow through a portion of the coil located in the part of a heating furnace subjected to the lowest furnace temperature, in simultaneously introducing a stream of redux condensate formed in the process to the heating coil at a point to cause such reflux condensate to initially flow through that portion ofthe coil maintained at the highest temperature in the furnace, in passing the heated commingled charging oil and reflux condensate-from the outlet of the coil to said enlarged conversion zone, in withdrawing unvaporized oil from the enlarged conversion zone without permitting the return of such withdrawn oil to the heating coil, and in maintaining a superatmosphericpressure on the oil undergoing conversion.

CARBON P. DUBBS. 

